Distortion-measuring system



Nov. 16 1926. 1,606,855

,E. F. WATSON DISI'ORTION MEASURING SYSTEM Filed May 10. 1923 2Sheets-Sheet 1 INVENTOR Waz i -ML 4 I ATTORNEY Nov. 16 ,1926.

, E. F. WATSON DISTORTI ON MEASURING SYSTEM Filed May 10. 1923 2Sheets-Sheet 2 IN vEN'roR Z'Wliibw I ATTORNEY Patented Nov. 16, 1926.

UNITED STATES PATENT OFFICE.

EDWARD l. WATSON, OF YONKERS, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONEAND TELEGRAPH OOHPANY, A CORPORATION OF NEW YORK.

DISTORTION-MEASURING SYSTEM.

Application filed May 10,

This invention relates to electrical measuring systems and particularlyto means for determining the existance and the magmtude of distortion ofsignaling impulses such as are used in printing telegraph systems.

In order to obtain eflicient operation of printing telegraph systems, itis necessary to eliminate the efiect of distortion upon the receivingapparatus connected with the line circuit. If a signal is distorted inthe course of transmission over a line circuit an impulse of wrongpolarity may be applied to a segment of the receiving distributor, whichin turn would produce an incorrect signal character in the apparatusassociated therewith. To determine the existance of distortion oftelegraph signals at the present time, it is necessary to discontinuetransmission of commerical service andsend a series of predeterminedimpulses over the line, which method is obviously ineflicient.

It is the object of this invention to provide means so associated withthe segments of the distributing ring of the receiving distributorwhereb the condition of the incoming signals, viz, the degree ofdistortion present may be readily determined while the circuit is usedfor commercial transmission.

This invention will be clearly understood from the following descriptionwhen read in connection with the attached drawing of which Fig. l is anembodiment of the invention in a system. using a brush distributor; andFig. 2 the invention applied to a cam operated distributor.

In Fig. 1, L represents a line over which signals may be transmittedfrom a distant station, not shown, to the station at which the apparatusshown in the drawing is located. The line L is shown connected with thearms 1 and 2 of abrid ed duplex telegraph system having connectedtherewith the artificial line AL to balance the real line. Bridgedacross the outer ends of the arms 1 and 2 is a polar relay 3, thearmature of which is connected with the grounded battery B and one ofthe contacts of which is connected with the relay 8 and thence throughthe jack J with the grounded battery B the polarity of which is oppositethat of B The relay 8,, which is responsive to the operation of thereceiving relay 3, serves to actuate the receiving apparatus of theprinting telegraph equip- 1923. Serial No. 688,124.

ment at the subscribers stations. The plug P which is connected with thewindin of the line relay 4, is adapted to be inserte in the jack J so asto effectively connect the line L, with the line relay 4. It will beseen that when the plug P is inserted in the jack J the circuitconnecting the batteries will include the winding of the line relay 4 inaddition to that of relay 8.

D represents the receiving distributor of the printer located at theterminal room for monitoring purposes. It consists of two concentricsegmental rings. The outer ring comprises a plurality of segments ofequal size and equally spaced designated S to S inclusive which areconnected with a plurality of selecting relays or magnets of which onlyone, viz, that connected with the segment S is shown. The outer ringalso includes the segments S and S,, the former of which is connectedwith the relay that controls the printing apparatus, and the latter ofwhich controls the starting apparatus of the distributor. The segmentswhich have been described perform the normal functions of the presenttype of receiving distributor and need no further explanation. They haveassociated with them cor-. responding segments S,,, S, and S of theinner ring by means of which the respective circuits are closed when thebrush 5 moves over the correspondin pairs of segments during therotation of t e brush arm. Interposed between the segments S and S ofthe outer ring are two segments S and S of the same size and similarlypositioned between the segments S and S are two inner segments S and SEach of the segments S and S is connected with its respective winding ofthe differential meter 6, which windings are connected together and thejunction thereof is connected through the right-hand contact of therelay 7 with the battery B The segment S is connected through the riht-hand winding of relay 7 and through t e winding of the selectingrelay 5 with the battery 13,. The battery B 7 is connected with theright-hand armature and also with the left-hand winding of relay 7-so asto form a lockin circuit through the left-hand armature an the uppercontact of rela 4 to ground. The said upper contact o relay 4 is alsoconnected with the segments S and S and the lower contact thereof isconnected with the segments S,

and S The selecting relay 5 and theotherwhich, for, the sake ofsimplicity is not shown since it forms no tion. Havin in mind theforegoing description of t e circuit in which'the invention is embodied,the nature of the invention will be clear from thefollowing descriptionof the mode of operation of the circuit.

- In the well known start-stop printing telegraph system, for eachcharacter transmitted there is always an open or start impulse followedby five selecting impulses which may be either open or closed, and aclosed or stop impulse. By the term open impulse is meant an impulse ofsuch character as a deenergize the line relay4 and allow its armature'todrop back,'and similarily by the term closed impulse is meant an impartof this invenpulse of such type as to energize the line relay and toattack its armature. The existence and the magnitude of distortion isdetermined by investigating the condition of the sixth impulse, viz,that which if undistorted, is applied by the line relay 4 while thebrush 5 is moving from segment S to S In order to get a clear picture ofthe nature of this invention, it is desirable to describe how thecircuit operates when undistorted, unbiased signals are applied by theline relay 4 to the distributor and its associated circuits. As hasalready been mentioned, the segments S and S are of the same size andare so located that when the distributor is receiving unbiased signalsthe sixth impulse will start to be received mid- Way between thesegments S and S Let it be assumed that the fifth impulse of the signalcharacter received over the line L is an open impulse. The armature ofrelay 3 would move to its lower contact thereby opening the circuit ofthe line relay 4 and allowing its armature to drop to its lower contactthereby disconnecting the ground from the segments S and S As the brush5 moves over the segments S and S and their corresponding inner segmentsS and S,,, the circuit from the battery 13,, through the winding of theselecting relay 5 and the right-hand winding of the relay 7 will be openby virtue of the removal of the ground from the segments S and S andconsequently relay 7 will not be energized. Furthermore current will notflow from battery B over the right-hand contact of relay 7 and throughthe differential meter 6, because the circuit is open at the uppercontact of the relay 4. Accordinglv no indica tion is given by themeter. ince, as assumed, there is no distortion. the line relay 4 willbe operated by the sixth impulse when the brush 5 passes the midpointbetween the segments S, and S Since this impulse is I closed, relay 4will be energized and its armature will be drawn to its upper contactthereby disconnecting the ground from the segment S Consequently thecircuit from battery B through the differential meter 6 to groundthrough the segments S and S will be open, and no indication will begiven by the meter.

Let us assume the other possible condition durin viz, t at in which thefifth impulse is a closed one. The reception of a closed impulse overthe line L will energize the relay 4 and attact its armature to itsupper contact thereby connecting the segments S,

and S to ground. As the brush 5 moves onto segment S a circuit will beestablished from battery B, winding of selecting relay 5, right-handwinding of relay 7, segments S, and S and upper contact of relay 4 toground thereby energizing relay 5 and also relay 7. The energization ofrelay 5 would operate the associated selecting magnet so as to transmitthe proper signal impulse, which feature, however, forms no part of thisinvention. The operation of relay 7 opens the contact of its right-handarmature and closes the contact'of its left-hand armature. By theopening of the contact of the right-hand armature, the circuit throughthe differential meter 6 will be opened, and no indication will be giventhereby so long as the relay 7 remains energized, which will continue aslong as the line relay 4 maintains its armature upon its upper contact.Since we have assumed the case of no distortion, the line relay 4 willremain energized by virtue of the fifth impulse, and will continue to beenergized after the brush passes to the segment S since the sixthimpulse is always a closed impulse. Consequently the circuit of themeter 6 is open and no indication will be given thereby under anycondition when the fifth impulse is a closed one.

Assuming that there is bias, and that the the reception of unbiasedsignals,

fifth impulse is an open one, the manner in which bias is indicated isas follows. lVhen the received signals are biased light viz, thearmature of the line relay is quicker to release and slower to operatethan when the signals are properly centered. The line relay will beunoperated when the brushes pass over segment S and will be unoperatedalso when the brushes pass on to segment 12 owing to the relativelyslower operation of the line relay to respond to the sixth impulsewhich, as stated, is a closed one. Since the line relay 4 is unoperatedwhen the brushes pass on to segments S and S current will flow frombattery B right-hand contact of the relay 7, one of the windings of thedifferential meter 6, segments S and S to-ground, thereby causingdeflection of the needle of the meter 6. The extent of deflection of themeter depends upon the amount of bias of the signals and to some extentupon the-speed o rotation of the distributor, so that for any givenspeed the amount of bias may be aproximated from the meter deflection.en the signals are biased heavy, viz, the line relay 4 releases slowerand o crates uicker than when thesignals are un iased,

t e sixth impulse will begin to be received when the brushesare onsegments S -and S anda circuit will be closed from battery B right-handcontact of relay 7 and through the other winding of the meter 6 and thecontacts S and S to ground thereby causing a deflection of the needle ofthe meter. This deflection is in opposite direction from the previousone and lndicates for any given distributor speed the approximate amountof biasing of the signaling impulse.

From the foregoin description it will be apparent that the di erentialmeter will indicate the existence and the relative magnitude ofdistortion of a signal consisting of a plurality of impulses, except inthose instances in which the fifth impulse is a closed impulse; and,except in such instances it will indicate whether the signals areproperly centered, (that is whether the relays are biased heavy orlight,) by the direction of deflection of the needle, and will give anindication of the amount of bias by the magnitude of its deflection. Thefact that it will not give an indication of bias when the fifth impulseis a closed impulse is not a serious disadvantage in view of the largenumber of a signal characters in which the fifth impulse is an open one.

The arrangement shown in Fig. 2 shows the application of this inventionto a printing telegraph system which is, in general, similar to thatshow in Fig. 1 but diifers therefrom by employing a cam-operateddistributor in place of the rotary brush dis-- tributor shown in Fi 1.The same reference characters have een used in both figures to representthe same parts. The camoperated distributor shown in Fig. 2 comprises asleeve 9, which carriers a plurality of cams, some of which, such as C CC C C and C may be seen while others which will be designated C to Cinclusive are (for the position of the sleeve shown in the figure) onthe opposite side thereof, away from the observer. The sleeve 9 iscarried by a continuously rotating shaft 10. This sleeve, however,crates only when a start impulse flowing t rough the winding of themagnet 12 withdraws its armature 13 from engagement with the cam 14 andthere by allows the friction clutch 11 to effectively connect the sleeve9 with the shaft 10. As the sleeve carrying its plurality of camsrotates in the direction indicated by the arrow, various contacts willbe closed in succession in the samemanner in which the movement of thebrush -of the rotary distributor of Fig. 1 closes in succession thevarious contacts of the said distributor.- The closing of contacts K toK inclusive controls the operation of selecting relays or magnets of theprinter in the samemanner in which s in Fig. 1.

The operation of thesystem in which the afore-described distributor isemployed is as follows: Let it be assumed that the first four impulsesof the signal character have been received and that each has operatedthe line relay 4 coincidentall with the operation of the contacts K toinclusive by means of the correspo-ndin cams C to C,

inclusive of the sleeve 9. e will furthermore assume that the fifthimpulse is an open one inasmuch as the invention is not designed toindicate the presence of distor- 'tion when the fifth impulse is a clwedone.

Since the fifth impulse is open, the line relay 4 will be deenergizedand its armature will touch and connect the left-hand contact to ground.As the sleeve 9 continues 'to rotate in the direction shown by thearrow, the cam C will move out ofthe enga ement with its associatedspring, there by pgiening the contact K and closing contact by theengagement of the cam C with its associated spring. As in the systemshown in Fig. 1,- the line relay 4 remains under the control of thefifth im-' Connected with contact K is a pulse of the signal characterthroughout the time that the contact K remains closed, assuming, ofcourse, that the signal impulse is undistorted. As the cam sleevecontinues to rotate, the contact K opens and K closes. If the sixthimpulse which, as

stated, is a closed impulse, is undistorted,

the line relay 4 will be energized and will operate coincidentally withthe closing of contact K by the engagement of the cam With the presenceof distortion, the system shown in Fig.2 operates in substantially thesame manner as that of Fig. 1. When the received signals are biasedlight, that is, when the armature of the line relay 4 is quick torelease and slow to operate, the line relay will be unoperated when thecontact K opens and remains so for some time after the contact K closes.This means that for an indefinite time after the closing of the contactK the armature of relay 4 remains in contact with its lefthand contactpoint. It will be seen, therefore, that current will flow from thegrounded battery B over a circuit embracing the right-hand contact ofrelay 7 the ri hthand winding of the meter 6, contact K and left-handcontact of relay 4, and consequently the needle of the meter 6 will bedeflected. The extent of the deflection depends upon the amount that thesignals are biased and to some extent upon the speed of rotation of thedistributing device.

When the signals are biased heavy,

I that is, when the line relay releases more slowly and operates morequickly than when the signals are unbiased, the sixth impulse will oerate the line rela 4: while the contact is still closed an therefore,before the operation of contact K It will be seen, therefore, that whilecontact K is closed current will flow from the grounded battery B over acircuit embracing the right-hand contact of relay 7, the left-handwinding of the meter 6, contact K and the right-hand contact of the linerelay 4, causing a deflection of the needle of the meter. Since in thisinstance the current is flowing through a different winding of the meter6 from that in which it flowed 'in the instance previously described,the

direction of deflection will be opposite from that in the previousinstance. It will, therefore, be seen that this method serves to shownot only the existence and, to some extent, the magnitude of distortionof the received signals but also serves to indicate, by the direction ofdeflection, the character of the biasing.

The invention possesses the great merit of simplicity, requiring only asmall amount of additional apparatus in order to effect the measurementof distortion of signals. While this arrangement may be applied to anyprinting telegraph distributor, its use would probably be limited to theprinting telegraph equipment located at the terminal oflice throughwhich the printing telegraph circuits are looped, inasmuch as such equiment is intended to be used to monitor t e service that is being givento various subscribers for printing telegraph service.

While this invention has been disclosed as embodied in a particular formand arrangement of parts, it is to be understood that it is not solimited but is capable of eration of the said relay and the saidswitching means, and an indicating device connected with predeterminedcontacts of the said switching means to show any distortion of apreselected impulse due to lack of synchronism between the operation ofthe said relay and the said switching means.

2. In a printing telegraph system in which each signal charactercomprises a plurality of impulses, the combination with a line circuitof a line relay controlled by impulses received from said line and aprinting telegraph distributor containing a pair of concentric segmentalrings, and a brush adapted to successively connect the radiallycorresponding segments of the outer and inner rings, and a currentindicating device con nected between certain segments of the rings ofthe said distributor and'a source of potential to indicate the degree ofbiasing of the signal impulses actuating the said line relay.

3. In a printing telegraph system in which each signal charactercomprises a plurality of impulses, the combination with a relayresponsive to signal impulses of a rotary distributor containing a pairof concentric segmental rings and having a brush arranged tosuccessively connect the radially corresponding segments of the outerand inner rings, and a current indicating device connected betweencertain segments of the rings of the said distributor and a source ofpotential to indicate biasing of the signals actuating the said relay.

4. In a printing telegraph system in which each signal charactercomprises a plurality of impulses, the combination with a rotarydistributor containing a pair of concentric rings, each ring having aplurality of signal and control segments and a plurality of distortionmeasuring segments between the said signal and the said control segmentsof a difl'erential current indicating device, each winding of which isconnected with its respective distortion measuring segment of the saiddistributor and a source of potential effectively connected with thesaid indicating device.

5. In a printing telegraph system in which each signal charactercomprises a plurality of impulses, the combination with a rotarydistributor containing a pair of concentric rings, one of which has aplurality of signal impulse segments, a printing impulse segment, anddistortion measuring segments interposed between the last of the saidsignal impu se segments and the said printing impulse segment and adifferential current indicating device, each of the windings of which isconnected with its respective distortion measurement segment, a sourceof potential connected with the said indicating device and means 'forcontrolling the time during which the circuit through the saidindicating device may be closed.

65'In a printing telegraph system in which each signal charactercomprises a plurality of impulses, the combination with a distributorcomprisin a plurality of switching means of a di erential currentindicating device connected with certain of said switchin means, a relayarranged to control the e ective application of the received impulses tothe said distributor, and a second relay adapted to effectively open thecircuit through the said indicating device when the last signal impulseis a closed impulse. 4

7. In a printing telegraph system in which each signal charactercomprises a plurality ments of equal size interposed between the lastsignal impulse segment and the printing impulse segment and having tworadially corresponding segments in the inner ring of the saiddistributor, the latter segments being connected with the upper andlower contacts respectively of the said line relay, a differentialcurrent indicating device havin each of its windings connected with oneo the said two segments in the outer ring of the said distributor andhaving a source of potential connected therewith, whereby any distortionof the stop impulse may be detected, and-a relay actuated Whenever thelast signal impulse is closed to open the circuit through the saidindicating device whereby a false indication of distortion may beprevented.

In testimony whereof, I have signed my name to this specification this8th day of May, 1923.

' EDWARD F. WATSON.

